1. Field of the Invention
The invention is related to dissipation of heat in a power inverting device. In a power inverting device, heat is generated within the device structure and it is necessary to dissipate the generated heat through a heat sink to an exterior housing. It is important to transfer the heat uniformly by ventilation and cooling techniques and by appropriate housing design.
2. Background of the Related Art
In a conventional power converter, common elements include a housing, an electrical circuit board assembly having power conversion capabilities, and a heat conducting plate attached to the circuit board assembly. Typically the heat conducting plate is mounted in direct contact with the circuit board and housing, either by abutting surfaces, heat conducting screws, or both, to dissipate heat through the housing. This manner of heat dissipation in conventional converters causes the areas of the housing directly in contact with the heat conductor plate to have higher temperatures than those areas of the housing not in contact with the heat conducting plate. This results in uneven heat conduction and inefficient dissipation, even with the use of a cooling fan circulating the air within the housing.
Furthermore, the conventional inverters having such aforementioned abutting surfaces or screwed connections between the heat conducting plate and the housing increase manufacturing requirements and tolerances as a result. Additionally, assembly becomes increasingly difficult. Therefore it is desirable to have an improved product in which the foregoing drawbacks of conventional power converters have been removed. The apparent advantages of the present invention over the above-described prior art and objects thereof follow accordingly.
It is an object of the invention to achieve even heat dissipation in a power converter.
It is a further object of the invention to simplify manufacturing requirements for the elements in a heat dissipating assembly.
It is another object of the invention to increase the ease of assembly of a heat dissipating assembly in a power converter.
A specific object of the invention is to provide air circulation channels between the heat conducting plate and the housing in a heat dissipating assembly.
It is a further object of the invention to extract heat directly from the circuitry of the power inverter into a heat conducting plate.
The invention is a power inverter having a heat dissipating assembly. The assembly includes a housing having a top wall and two opposing side walls, and a printed circuit board assembly supported within the housing. The printed circuit board assembly comprises a printed circuit board equipped with power converting components. A heat sink plate is supported on the printed circuit board in a spaced configuration so that a space exists between the heat sink plate and the printed circuit board.
The printed circuit board assembly includes a plurality of mosfets inserted into the printed circuit board. The mosfets are connected to the circuitry of the power converting components, and the heat sink plate abuts against a first side of the mosfets at an upper end of the mosfets. This creates the space that exists between the heat sink plate and the printed circuit board. The heat sink plate is secured to the first side of the mosfets by a support bar abutting against an opposing side of the mosfets by screws passing through the support bar and the heat sink plate.
The heat sink plate is L-shaped and a side wall of the heat sink plate is mounted perpendicularly to the printed circuit board. A top wall of the heat sink plate extends above the printed circuit board assembly parallel to the printed circuit board. An interior top surface of the top wall of the housing is substantially parallel to the top wall of the heat sink plate so that a ventilation space exists between the entire top wall of the heat sink plate and the interior top surface of the housing. This ventilation space allows heat from the heat sink plate to dissipate to air in the ventilation space before dissipating to the housing. A second ventilation space exists between the side wall of the heat sink plate and an interior surface of the side wall of the housing adjacent thereto.
The power inverter assembly further includes a front end plate and a rear end plate secured to the housing in a manner so as to enclose the printed circuit board assembly and the heat sink plate. At least one of the front end plate and the rear end plate having a plurality of ventilation holes through which air can pass to and from the interior of the housing. An intake fan may be mounted to one of the front end plate and the rear end plate to intake cooling air and circulate air within the housing. The intake fan serves to increase heat dissipation from the heat sink plate to the air and then to the housing. The front end plate and the rear end plate are also provided with electrical outlets, and on/off switch, and a fuse. A base plate mounted to bottom edges of the two opposing side walls of the housing in a manner so as to enclose the printed circuit board assembly and the heat sink plate within the housing, the front end plate, and the rear end plate.
The invention additionally features the side wall of the heat sink plate having heat dissipating fins extending out from the side wall of the heat sink plate toward the interior surface of the side wall of the housing within the ventilation space existing therebetween. An exterior surface of the housing is provided with a plurality of heat dissipating fins. These fins further enable heat dissipation.